The UN's top envoy for Yemen pushed for all sides to de-escalate the fighting around Hodeida during a visit earlier this month to broker negotiations. "It is essential for him to be given the time that he needs to facilitate a negotiated solution that avoids conflict in the city and we support his efforts to do so".

The rebels control much of northern Yemen, including the capital, Sanaa.

For the past two weeks, Yemen government troops backed by the coalition have been closing in on Hodeida, which they claim is being used by Huthi rebels to smuggle weapons.

By late today, key lawmakers had begun losing faith in U.S. efforts to convince Saudi and UAE military officials to stop the assault, after The Wall Street Journal reported that the UN's shuttle diplomacy failed to move UAE officials and that the Donald Trump administration had given the operation "a blinking yellow light".

Nearly 10,000 people have been killed since the alliance launched its intervention, contributing to what the United Nations has called the world's worst humanitarian crisis.

"I have spoken with Emirati leaders and made clear our desire to address their security concerns while preserving the free flow of humanitarian aid and life-saving commercial imports", he said. "The US has begged Saudi/UAE coalition not to attack the humanitarian aid port of Hudaydah". The UN humanitarian coordinator for Yemen has warned such an attack would be a "catastrophe". This incident took place on Friday.

The conflict in Yemen has left almost 10,000 people dead in what was already the Arab world's poorest country.

Since 2015, Saudi Arabia has been leading a military campaign to push back the Huthis and restore the internationally recognized government to power.

An alarming 22.2 million people in Yemen - the Arab world's poorest country - need some kind of humanitarian or protection assistance, according to the United Nations Office for the Coordination of Humanitarian Affairs (OCHA).